Biphasic changes in hemoglobin A1c concentrations during normal human pregnancy

Richard L. Phelps*, George R. Honig, David Green, Boyd E Metzger, Marilynn C. Frederiksen, Norbert Freinkel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


Analyses of hemoglobin A1c concentrations were performed throughout gestation in 377 nondiabetic women. We observed significant biphasic changes in hemoglobin A1c concentrations, with an initial gradual decline to a nadir level at 24 weeks, followed by a subsequent slow reascension to peak near term. All these changes fell within the usual range of normal values for hemoglobin A1c. Values for plasma glucose estimated 1 hour after a 50 gm oral glucose load in 1,756 normal gravid women showed similar biphasic excursions, with the nadir occurring 4 weeks earlier, i.e., at 20 weeks' gestation. We conclude that the small but significant changes in hemoglobin A1c during the course of normal gestation reflect, with an appropriate displacement in time, the biphasic alterations in mean blood sugar that characterize the sequential changes in glucoregulation during normal pregnancy.

Original languageEnglish (US)
Pages (from-to)651-653
Number of pages3
JournalAmerican Journal of Obstetrics and Gynecology
Issue number6
StatePublished - Nov 15 1983

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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